How are you walking him? Is he in your arms? In a sling? I think that will help understand what he's really attached to...
My first was a sling baby and, honestly, there were so many advantages to that even if the whole "holding to sleep" thing got old from time to time. She needed physical contact to sleep for a long time. I say this just to give you some comfort if some of my suggestions that worked for my second don't work for you.
My second is a much less physical baby in terms of her need to be held. For her, intimacy comes from things like hiding together under a blanket or sharing food and other slightly less snuggly things.
Do you drive? If so, does your baby sleep in the car? I know this not the most environmental suggestion but in order to wean my younger off nursing to sleep during naps I structured my day so I was always in the car during nap time...and then did the back breaking task of hauling a sleep toddler in car seat into the house. URGH! It was rough...and we still haven't found a non-motion solution for naps.
BUT, we've had great success at night, which I thought was going to be the more difficult one. I suggest a good routine and just talking to your LO about the new plan. Perhaps walk, lay down, walk, lay down, walk lay down...as many times as it takes the first night. Or, what we did (nursing was the thing we wanted to remove from the sleep routine) was DC could be downstairs with her dad as much as she wanted but if she wanted to be up with me she had to lay in her bed alone. This would NOT have worked with my first child in a million years...but I worked so, so well for my baby. I was getting some signals from her that maybe she would be a better sleep-alone sleeper and I think she is. I still bring her in "the big bed" every night when I go up but this solution is one that works for her. You could certainly do the same with a family bed.
Another though if it's motion that your LO likes is to get a stroller and walk - good exercise, the nights are longer (presumably) and I have found that to be a nice routine/way to end the day. If you have a partner, you could share that task too...and a bonus is that it's something most other caregivers could do if you want to move in that direction.
For me, I think the key is to just change one thing. Let the child have what they most attached to (within reason) but find a way to make that work for you. I think a little compromise is fine (even good!) for kids as they move into the toddler stage.